body {
    background-image: url("../img/bg.jpg");
    background-size: cover;
}
form {
    margin: 100px auto;
    width: 500px;
    background-color: rgb(255,255,255,.8);
    padding: 50px 0 50px 100px;
}
form input {
    height: 30px;
    width: 250px;
    margin-bottom: 20px;
    margin-left: 5px;
}
form input[name = captcha]{
    width: 100px;

}
form img{
    height: 30px;
    vertical-align: middle;
    margin-left: 8px;
}
form button{
    height: 30px;
    width: 120px;
    border-radius: 8%;
    margin-left: 55px;
}
.error{
    margin-left: 20px;
    color: red;
}